A horizontal suction duct can be provided for removing broken pieces of yarn and/or roving pieces, hereinafter referred to generally as fiber fragments, from a spinning machine, preferably a spinning machine used to manufacture yarn or threads, the spinning machine being a ring or other spinning machine or a fly frame or a drafting frame forming a part thereof. Each suction duct for the spinning machine has intakes at each of a plurality of working positions of the spinning machine, i.e. the positions found on one longitudinal side of the spinning machine.
Many known spinning machines have a broken thread or roving suction apparatus. These suction apparatuses and improvements thereon are described in a number of patents, for example U.S. Pat. No. 2,819,579, U.S. Pat. No. 2,946,174, Swiss Patent No. 315287, German Patent No. 938,653, German Open Patent Application No. 30 25 064, Austrian Patent No. 182344, British Patent No. 913,673, German Printed Patent Application No. 24 50 627, and German Open Patent Application No. 26 43 902.
In general, the suction apparatus acts to pull away and remove broken threads or roving from the drafting frame, spinning rotors, or other working components supplied with sliver, pieces of thread or the like.
Such apparatus can also be used in spinning machines which make thread, such as ring spinning machines, bell spinning machines, open ended spinning machines and the like.
Large scale spinning machines used in factories having a plurality of working positions also can have a suction apparatus with an intake nozzle or opening at each working position.
In these machines the thread or yarn is warped or drawn, e.g. in a drafting frame, twisted, wound up on bobbins as sliver, stored in cans, or sent to other spinning or twisting machines for further processing. By roving I generally mean pieces of thread, sliver, or the like which usually have a slight twist, although roving in many cases is free from twist.
All of these machines can be described as yarn-handling machines with individual working positions for each of the multiplicity of yarns handled.
The number of working positions of a spinning machine thus usually corresponds to the number of stations where yarn, thread or the like is supplied.
The stations where yarn are supplied are in the case of a ring spinning machine, its spindles so that the number of spindles corresponds to the number of working positions in this machine.
In an open-ended spinning machine the number of spinning rotors corresponds to the number of working position and in a flyer frame each working positions is a respective flyer.
It is also conceivable that one supply station can be associated with several working positions, which are provided with suction intakes of the suction duct, when several threads run from a common supply station. In the case of broken thread or roving at the concerned working position the fiber, thread or like fragments are removed by the suction apparatus.
In many cases, particularly in spinning machines used to manufacture yarn, both longitudinal sides of the spinning machine have a row of working positions. There are also spinning machines, including machines for the manufacture of yarn, which have working positions on only one longitudinal side of the machine or several rows of working positions, for example a flyer frame.
Every row of working positions is usually associated with a single horizontal suction duct, which can have suction intakes in its peripheral walls associated with this row of working positions.
Alternatively these suction intakes can be provided in suction tubes or nozzles connected to the suction duct which is the more commonly used design. Commonly a single suction opening is provided per working position but in many cases at least two suction openings are provided per working position, for example when two rovings running adjacent each other are twisted together to form a common thread.
In very long spinning machines each row of working positions is associated with at least two horizontal suction ducts. However one horizontal suction duct per row of working positions is the standard situation.
A single suction apparatus can have a single suction duct or a plurality of suction ducts. Each suction apparatus has an air blower mechanism or an axial ventilator, a radial ventilator, or the like and further at least one filter device like a fiber filter or the like which acts to remove fiber pieces, strands or the like carried along with the flowing air.
One such suction apparatus can be directly mounted in a spinning machine or a single suction blower can be associated with a plurality of machines or conversely each machine can have two or more suction blowers. A single large broken thread and/or roving suction apparatus can be provided for a plurality of spinning machines and can have a central air blower mechanism to which the horizontal suction ducts associated with it are connected by one collector duct or a system of collector ducts.
The energy consumption of a broken thread and/or roving suction apparatus is dictated by the total quantity of air extracted by it from the working positions per unit time.
The suction capacity of a suction duct must be dimensioned for the case in which broken threads alone, broken roving alone, or some mixture of broken roving and threads is present at each station especially immediately after a batch change or after doffing. Of course after a batch change broken threads or rovings are found at all working positions, and fresh thread or roving must be connected at all the working positions. This can be effected by a working column member or by a threading carriage and lasts a short time, for example 10 to 30 minutes.
For this reason the usual suction apparatus has its suction capacity dimensioned so that in the extreme case of startup the fiber pieces, threads or the like from the draw frame, spinning rotors, or the like can be simultaneously removed from all affected working positions, e.g. upon doffing. This suction capacity has hitherto been fixed or constant during the operation of the spinning machine and also during doffing.
However it is also known to reduce the total air flow per unit time of the flowing air by throttling individual intake nozzles associated with selected working positions of a spinning machine and to open the individual tubes only when a thread break occurs at the associated working position position (U.S. Pat. No. 2,819,579).
In view of the normally very large number of working positions and thus suction tubes the cost of a system with individual nozzle valves is very high, since every working position requires a thread break sensor. Also the continuous suction of air from all working positions in a spinning machine is desirable, since then in in all case broken threads or broken roving, sliver, or the like are immediately removed. Also lint blown off in such a spinning machine is continuously removed. Thus contamination of the spinning machine by fuzz or dirt is considerably reduced.
For many years the broken thread or roving suction apparatus with constant suction capacity has been used. Additionally suction apparatuses can also be provided to transport fragments of broken thread, roving or sliver collected from various working positions in a central collection chamber to a processing room for recycling as taught in U.S. Pat. No. 2,946,174. In both cases the required air feed capacity is however quite high and causes a considerable energy expenditure.
Other means for directly sensing the flow rate of broken fibers in a suction duct have been taught for general control of suction duct operation (Swiss Patent No. 315,287 and Austrian Patent No. 182,344). But these devices involve a time delay, fairly complicated electronics and additional expense.